1. Field of the Invention
The present invention relates to methods and apparatus for joining webs of pouches such that the asepsis of the interior of the webs is maintained, and, in particular, methods and apparatus for joining webs of pouches made from a tube-shaped web of a heat-sealable polyolefin to maintain asepsis of the interior of the pouches.
2. Prior Art
Plastic bags or pouches having sterilized interiors are commonly used to store material, such as food products, for long periods of time. Since the pouches are impervious to microorganisms, the asepsis of the contents can be maintained indefinitely.
One type of plastic pouch is made of a heat-sealable polyolefin such as polyethylene or polypropylene. These pouches are manufactured through a process which includes making an aseptic web of pouches by first blow-extruding a continuous closed tube using a non-contaminating gas, then dividing the tube by means of partial, transverse heat seals into a series of interconnected pouches which intercommunicate with each other in a closed system by means of a continuous channel which runs across their open mouths. Such a method is discussed more fully in applicant's U.S. Pat. No. 4,021,283 issued May 3, 1977.
Such a web of pouches is filled by piercing the wall of an end pouch in the area adjacent the continuous channel and inserting a pipe along the channel. The pipe typically has an orifice which can be positioned to discharge material into the mouths of the individual pouches. In order to maintain the asepsis of the web of pouches, the filling pipe is preferably covered by a sterilizing boot made of a plastic material which is attached to the leading end of the sealed web of pouches. The leading end of the filling pipe is conical in shape to facilitate puncturing the wall of the boot and the wall of the web of bags so that the sterilizing pipe can be inserted into the continuous channel.
As set forth in applicant's U.S. Pat. No. 4,171,604, issued Oct. 23, 1979 the web of pouches is joined to the boot by first placing a patch saturated with an appropriate sterilizing agent on the web of internally sterile pouches and securing it thereto by means of double-sided tape. The portion of the web carrying the patch is placed over the boot so that the double-sided tape causes the two tubular members to be held together. The pointed end of the filling tube may then pierce the wall of the boot, pass through the sterilizing patch, and pierce the adjacent wall of the web of pouches to enter the common channel, without exposing the interiors of the boot and channel to contaminated ambient air.
Webs of pouches typically are packed and shipped in containers, usually made of fibreboard, and are fan-folded in the containers. Depending on the size of the pouch, the pouches may be folded two or more abreast. For many high volume operations, it is often necessary to fill a number of pouches larger than the number of pouches normally joined in a single web and packed in a single container. One method is to fill the pouches of a single web from a single container, then remove that web of pouches completely and begin the process again for a second web of pouches in a second container. However, this method has a disadvantage in that a substantial amount of time is required to resterilize the filling pipe and re-insert the filling pipe into a continuous channel in a succeeding web of bags.
Accordingly, there is a need for a method and apparatus for joining internally aseptic webs of bags or pouches together to form a continuous web of pouches without destroying the internal sterility of the pouches and to minimize, if not eliminate, production downtime caused by the prior art methods of joining webs.